Glass parts for forming cathoderay tube envelopes



Sept. 3, 1968 A. c. MEIRESONNE 3,399,799

GLASS PARTS FOR FORMING CATHQDE-HAY TUBE ENVELOPES I Original Filed Aug.24, 1966 5 Sheets-Sheet 1 INVENTOR. 4e777 I fife/pirauw BY a M 41 Sept.3, 1968 A. c. MEIRESONNE 3,399,799

GLASS PARTS FOR FORMING CATHODE-RAY TUBE ENVELOPES Original Filed Aug.24, 1966 5 Sheets-Sheet 2 Sept. 3, 1968 A. c. MEIRESONNE GLASS PARTS FORFORMING CATHODE-RAY TUBE ENVELOPES s Sheets-She et 3 Original Filed Aug.24, 1966 United States Patent 3,399,799 GLASS PARTS FOR FORMING CATHODE-RAY TUBE ENVELOPES Arthur C. Meiresonne, Columbus, Ohio, assignor toOwens-Illinois, Inc., a corporation of Ohio Original application Aug.24, 1966, Ser. No. 579,448, now

Patent No. 3,322,522, dated May 30, 1967. Divided and this applicationFeb. 20, 1967, Ser. No. 617,304

6 Claims. (Cl. 220-21) ABSTRACT OF THE DISCLOSURE This invention relatesto hollow glass parts, each having a distinctively-contoured annularflange portion adapted to permit improved scaling to another hollowglass part having a complemental sealing surface, such parts being ofparticular utility in forming cathode-ray tube envelopes and the like.

This application is a division of my copending application Ser. No.579,448, filed Aug. 24, 1966, which was based upon original applicationSer. No. 257,458 filed Feb. 11, 1963, and now abandoned. The aforesaidapplication Ser. No. 579,448 has now matured into the US. Patent No.3,322,522 issued May 30, 1967.

In the manufacture of glass envelopes for use in electronic tubes suchas television tubes and cathode-ray tubes of other types, it isconventional to join 'a hollow glass funnel and a hollow glass faceplate. The funnel is conventionally made by centrifugal casting and asealing edge is formed on the large end of the frusto-conical portion ofthe funnel by scoring the heated funnel and causing a portion of the endof the funnel to ring off to define the sealing edge on the funnel. Theface plate is conventionally made by pressing a charge of glass to forma face plate portion and an annular peripheral flange portion which hasa sealing edge defining a substantially flat planar surface. The parts'are conventionally joined to one another by placing in a lathe andapplying heat to the sealing edges. As soon as the parts are hot enoughto show red color, electrical current is introduced to facilitateheating and after proper heating, the parts are brought together whilecontinuing the heating.

Because the sealing edge on the funnel is made by ringing oif, glassirregularities are found in the sealing edge 'and it is necessary tothermally shock the sealing edge of the funnel by applying heat toremove these glass irregularities. Thus, the sealing edge of the funnel,which is also usually thinner than the edge of the face plate, has moreheat applied thereto and it is diflicult to subsequently heat thesealing edge of the face plate sufliciently to provide a complete andsatisfactory joint.

It is therefore an object of this invention to provide a face platehaving a novel sealing edge design which facilitates the thermal fusionof the face plate to the funnel.

It is a further object of the invention to provide such a face platewhich facilitates the heating of the sealing edge of the face plate andpermits a more eflicient heating of the sealing edge.

It is a further object of the invention to provide 'an improved jointbetween the funnel and face plate.

Basically, the invention comprises forming the flange portion of theface plate such that the sealing edge has the major portion thereoflying on the radially innermost side of the axial center line of thecross section of the flange portion. This results in a small volume tosurface ratio at the sealing edge so that the heating rate of thesealing edge will occur more rapidly. Since the major portion of thesealing edge is in the innermost side of the axial center line of thecross section of the 3,399,799 Patented Sept. 3, 1968 ice flange portionand has a small volume to surface ratio, this edge will initially heatfaster, thus taking and conducting the electrical current more readilyresulting in heating the sealing edge in a line which is on theinnermost side of the axial center line of the cross section of theflange 'as compared to heating from the outer surface with theconventional design. This provides a better and more etficient hermeticjoint between the parts.

In the drawings:

FIG. 1 is a fragmentary sectional view through a molding apparatus forforming the face plate.

FIG. 2 is a plan view of a face plate embodying the invention.

FIG. 3 is a fragmentary sectional view on an enlarged scale taken alongthe line 3-3 in FIG. 2.

FIG. 4 is a fragmentary sectional view on an enlarged scale taken alongthe line 44 in FIG. 2.

FIG. 5 is a fragmentary sectional view of an enlarged scale taken alongthe line 5-5 in FIG. 2.

FIG. 6 is a partly diagrammatic sectional view showing the relativeposition of the funnel and face plate during an initial stage in thesealing of the funnel and the face plate.

FIG. 7 is a view similar to FIG. 6 showing the relative positions of theparts during a further stage in the sealing thereof.

FIG. 8 is a sectional view showing the final joint between the parts.

FIG. 9 is an elevational view of a cathode-ray tube envelope after thefunnel and face plate have been joined.

Referring to FIG. 1, the face plate 10 embodying the invention is madein a conventional apparatus by pressing a charge of glass. Suchapparatus includes a mold 11 into which the charge of glass is placed, aremovable ring 12 and a plunger 13 which is pressed downwardly into thecharge of glass and cooperates with the mold 11 and ring 12 to form thecharge into the desired shape. The plunger 13 is formed with an interiorliquid distributor 14 which provides liquid to cool the interior surface15 of the mold. The plunger and distributor are mounted on a ram 16.

In accordance with the invention, the interior surface 17 of the ring 12is shaped to provide a specific configuration to the flange 18 of theface plate 10, The flange 18 comprises a peripheral wall that extendsaround the face plate portion 19 of the face plate 10.

As shown in FIGS. 3, 4 and 5, the surface 17 is shaped so that theexterior surface of the flange portion 18 includes a first portion 20tapering slightly inwardly toward the edge of the flange portion 18, asecond portion 21 tapering inwardly at a slightly greater angle and asealing edge 22 comprising a head which is arcuate in cross section anda short ledge 23 which is needed to provide strength to the portion 24of the ring 12.

The surfaces 20, 21 are so positioned with respect to the cross sectionof the flange 18 that the center R of the radius of the head 22 and, inturn, the major portion of the bead 22 lies radially inwardly of anaxial center line C through the cross section 18. Axial center line C isdrawn by connecting the centers of the flange cross section between themold seam, formed by the mold 11 and ring 12, and the area which isdistorted in the sealing process. In other words, the cross section ofthe flange portion 18 is unsymmetrical adjacent the sealing edge withthe greater portion of the sealing edge lying radially inwardly of theaxial center line through the cross section of the flange portion.

When a flame is applied to the sealing edge, as presently described, thesealing edge will be more readily heated and therefore will reach atemperature such that current will pass therethrough sooner. Thispermits a better balance of the timing of the heating of the funnel edgeand the face plate edge so that a better joint is achieved between theface plate and funnel.

Referring to FIGS. 6-8, the funnel 25 comprises a frusto-conical portionwhich has a sealing edge 26 at the larger end thereof. The sealing edge26 is conventionally formed in the funnel by grooving and annularlyscoring the funnel after the funnel has been centrifugally cast from acharge of glass and permitting a ring or moil of glass to be broken offof the funnel due to an annular pattern of fracture sources which resultin moil separation when the funnel is cooled. The resultant sealing edge26 is often formed with irregularities that must be re moved bythermally shocking the edge of the funnel by application of a flame F(FIG. 6).

The sealing operation is then continuedby application of an additionalflame F on the flange portion of the face plate. conventionally, thesecond flame F is not applied to the edge of the face plate until theflame F has heated the-sealing edge 26 sufficiently to removeirregularities.

After the heating of, the sealing edge of the face plate has beeninitiated and the parts are heated to a red heat, an electric current isapplied as by passage through the gaseous flame, and the sealing edgesare then forced together axially as shown in FIG. 7.

The provision of the sealing edge 22 of the face plate radially inwardlyof the major portion of the cross-section of the flange 18 of the faceplate permits the flame F to heat the sealing edge more completely andmore rapidly so that when the parts are brought together, that part ofthe sealing edge which is at the highest temperature is radially inwardof the major portion of the crosssection thus giving the inner surfaceof the seal added strength. In addition, the higher temperature of thesealing edge 22 will permit the electrical current to flow through thesealing edge 22 as well as the Sealing edge 26 to facilitate theformation of a better joint.

The provision of the tapered surface 21 on the flange portion 18 permitsthe flame F to be applied at a right angle to the surface 21 furtherfacilitating the heating of the sealing edge. This may be contrasted toprior art constructions wherein the flame F was conventionally appliedalong a radial direction.

The final joint as shown diagrammatically in FIG. 8 provides for a morecomplete and thorough fusion and is therefore a more perfect hermeticseal between the parts (FIG. 9).

What I claim is:

1. For attachment to a funnel-shaped body to form a till cathode-raypicture tube by thermal fusion, a hollow glass 'part 'comprisin g i i aviewing portion and a peripheral flange portion extending axially awayfrom said viewing portion, said flange portion having an annular sealingedge defining a substantially planar sealing surface,

the 'cross sectional'area of the flange portion adjacent the sealingedge being unsymmetrical such that the major portion of the area thereoflies radially inwardly of a center line extending axially through thecross-section of said flange portion, and

a continuous peripheral bead on said sealing surface,

substantially the entire cross-section of said bead lying radiallyinwardly of said center line.

2. The hollow glas's part set forth 'in claim 1 wherein said area'ofsaid flange portion adjacent said sealing edge has an outer surface thattapers gradually inwardly away from the viewing portion toward thesealing edge.

3. The hollow glass part set forth in claim 1 wherein said sealing edgeincludes a substantially flat annular surface positioned radiallyinwardly of said bead.

4. The hollow glass part set forth in claim 3 in combination with asecond hollow glass part having a frustoconical wall with an annularsealing edge, said sealing edge having been produced by ringing off amoil of glass, the thickness of the sealing edge of said second hollowpart being less than the average thickness of the flange portion of thefirst hollow part.

5. The hollow glass part set forth in claim 1 in combination with asecond hollow glass part having a frustoconical wall with an annularsealing edge, said sealing edge having been produced by ringing off amoil of glass, the thickness of the sealing edge of said second hollowpart being less than the average thickness of the flange portion of thefirst hollow part.

6. The hollow glass part set forth in claim 1 wherein said area of saidflange portion adjacent said sealing edge has an outer surface thattapers gradually inwardly away from the viewing portion toward thesealing edge.

References Cited UNITED STATES PATENTS 1/1961 Stutske 2202.1

6/1962 Knochel et al.

MARTHA L. RICE, Primary Examiner.

